I don't need a heater in Baja California, Mexico, but I still wonder why the heater in our '96 Dakota Sport 3.9L 4X4 blows cool air. I am refilling the cooling system after a flush and it is recommended to run the heater during the process. I don't see any under-hood valve that manages the heater intake hose (hot side) like many vehicles have, so I don't know what the problem is. I only see both heater hoses entering the firewall on the driver's side.


I did notice the dash lever to adjust heat from cool to hot was very stiff, but the lever still moved all the way to the right. Thanks for any input.

 

1. Make sure you’re not low on coolant.
2. Your thermostat might be bad
3. Your heater core could be clogged or shot

Does your engine temp gauge show it is warming up normally? If not, probably a thermostat.

Get your engine warmed up. Feel your two heater hoses going into the firewall. If one is hot and the other is not then your heater core would need backflushing or replacing.

 

After running the engine for five minutes or ten minutes at a time over the past 24 hours, the heater finally put out some warmer air. There must have been one heck of an air pocket in the cooling system somewhere. A added a little water after the first five/ten minute "warm up", and then it did not take any more water during/after the subsequent warm-ups.

 

Low coolant will cause lack of heat.

Back flushing the heater core is a good maintenance item. Not a difficult job. Watch a few You Tube videos.